Most of the other sporting achievements in the top twenty were made by Americans.
Romanian gymnast Nadia Comanecis seven perfect 10 scores at the 1976 Montreal Olympics was third in the list with US baseball star Joe DiMaggios 56-game hit streak in 1941 being placed fourth. Third was Jesse Owens setting four world records in 70 minutes at a 1935 athletics meet.
http://www.forbes.com/…/athletic-achievements-bannister_cx_05athleticachievland.html